The present invention relates to an antiseptic composition and more particularly a foam or cream for disinfecting the skin. It is especially useful against bromidrosis.
A large number of compositions for various disinfecting operatitons are known; when hygiene purposes are concerned, particularly the disinfection of regions of the skin where odours have a tendency to originate, the problem becomes rather difficult, because it is necessary to reconcile an efficient antiseptic effect with perfect harmlessness with respect to the skin. Now this result is often difficult to achieve, particularly where bromidrosis of the feet is concerned; it has in fact been found that, in the fight against the unpleasant and insalubrious effect, most of the known disinfecting agents are found to have an irritating effect or are even inefficient; on the other hand, given the complexity of the flora of the microorganisms which cause the bromidrosis, the action of the known antiseptic agents is generally incomplete and of short duration.
The present invention provides the solution to this delicate problem by the application of a new and very efficient composition, of which the action is lasting, because of the fixation of certain active agents on the skin, without any irritation being caused. Applicable to all kinds of hygienic care, the composition according to the invention is particularly effective in combating bromidrosis of the feet. While this composition may be liquid or creamy, its preferred form is a greasy foam which has very good cosmetic qualities in addition to its microbicidal and fungicidal activity.
The present invention results from the unexpected discovery that certain known ampholytic surface-active disinfectants, which in usual low concentrations have practically no effect on the bromidrosis, while at higher concentrations become irritant to the skin, can show extremely active at certain determined concentrations, and remain non-irritant, if special precautions are taken in accordance with the present invention.
It is known to employ, as disinfectants, amino acids with several amine functions, carrying at the end of their chain a heavy linear aliphatic radical, particularly a C.sub.8 to C.sub.18 alkyl, which have the advantage of not showing toxicity for human beings. Generally employed in concentrations of the order of 0.05 to 2% by weight, these agents act in an efficient manner against a large number of microorganisms, such as staphylococci, corynebacterium, coli, salmonella, pseudomona, etc. However, at concentrations exceeding about 0.3%, these amino acids become irritant to the skin, and this makes it necessary for the manufacturers thereof to block the amine functions ("Doprinate") or to decrease the number thereof; however, the activity against the bromidrosis is then considerably reduced. On the contrary, the amino acids in question, for instance, omega-N-alkyl-1-triaza-alkanoic acid, particularly "Dodicin" (The Merck Index, 1968, page 396) become very efficient against bromidrosis when they are used in concentrations higher than 0.3%, generally about 0.5 to about 5% by weight: unfortunately with these relatively strong concentrations, these agents have disadvantages as regards the skin.
In fact, this drawback has already been mentioned in 1958, in the British Pat. No. 836,956 on page 2, lines 7-10. The patent teaches that exceptionally n-dodecyl-1,3-propylenediamino-acetic acid hydrochloride, even in a 10% solution, does not cause any visible redness on the skin. However, while that is true with a "cloth-skin test" (page 2, lines 30-34 of the patent) which lasts a short time, the result is quite different when the above compound is repeatedly applied to human or animal skin: then, even an aqueous 0.3% solution of it produces irritation after some days.
Thus, all the amino-acids containing disinfectant compositions, described for example in U.S. Pat. Nos. 2,717,850 and 3,574,850 are harmful to skin when they have 0.3% or more amino-acid and are used repeatedly. Such compositions are suitable for disinfecting by a wash made once or from time to time, but cannot be left in contact with the skin for several hours or days.
The above drawback is undoubtedly the reason for which, in spite of the excellent disinfectant properties of amino-acids bearing a rather long aliphatic chain, these compounds have not been used until now in cosmetic or hygienic compositions designed for long time contact with the skin.